聚苯乙烯负载席夫碱Mo(Ⅵ)配合物合成、表征及其在环己烯环氧化反应中的催化活性

合成了聚苯乙烯负载乙二胺缩水杨醛席夫碱与Mo(Ⅵ)的配合物,并对其结构进行了表征.该配合物催化环己烯环氧化反应与小分子配合物MoO₂(acac)₂相比,具有更优良的催化活性和选择性;建立了催化剂中Mo分析和环氧环己烷气相色谱分析新方法;探讨了配合物及环氧环己烷合成过程诸因素的影响;优化了环氧环己烷合成条件,即以n(t-BuOOH)=0.1mol计,n(C₆H₁₀)∶n(t-BuOOH)=3∶1,溶剂5mL,反应温度80℃,时间60min.在该条件下,环氧环己烷收率(以t-BuOOH计)99.2%以上,质量分数约99.5%(GC检测).催化剂循环使用5次后,未见活性明显下降,环氧环己烷收率(以t-BuOOH计)仍接近99%.

Synthesis and Characterization of Polystyrene-grafted Molybdenum (Ⅵ) Schiff Base Complex and Its Catalytic Activity in Epoxidation of Cyclohexene

Molybdenum(Ⅵ) Schiff base complex derived from salicylaldehyde and ethylenediamine grafted in polystyrene-divinyl benzene(PS) supporter, was synthesized and characterized by IRspectra.The macromolecule Schiff base acts as uninegative bidentate ligand and bonding occurs through the hydroxyl oxygen and nitrogen atoms.The Mo(Ⅵ) complex grafted in polystyrene as the catalyst has been used in epoxidation process of cyclohexene, and its catalytic activity and selectivity have also been investigated.The experimental results show that the complex possesses an excellent activity and selectivity for epoxidation of cyclohexene.The effects of many factors on the graft process of PSsupporter and synthesis of cyclohexene oxide have also been discussed.New analysis method of amount of Mo in the catalyst and gas chromatogram (GC) method of epoxycyclohexane analysis have been set up.The optimum reaction condition has been obtained by orthogonal experiment design, that is, according to n(t-BuOOH)=0.1 mol, n(C₆H₁₀)∶n(t-BuOOH)=3∶1, volume of solvent is about 5mL, reaction temperature 80 ℃, reaction time 60 min, and weight of molybdenum in the catalyst is 2.08×10^-2g.Under this condition, based on amounts of t-BuOOH, the yield of epoxycyclohexane is more than 99.2%, purity of epoxycyclohexane is about 99.5% by GCanalysis.The catalyst after being used circularly for 5 times still possesses higher catalysis activity and selectivity, the yield of cyclohexene oxide approaches 99% under the above-mentioned reaction condition.